I've fixed it just using this method:
function removeTinyMCE() {
tinyMCE.execCommand('mceFocus', false, 'txtAreaContentPage');
tinyMCE.execCommand('mceRemoveControl', false, 'txtAreaContentPage');
}
and calling before addControl
afterUpdate: function (element, position) {
removeTinyMCE();
tinyMCE.execCommand('mceAddControl', false, 'txtAreaContentPage');
}